Paper product and process of making the same



Patented July 22, 1930 UNITED STATES PATENT OFFICE.

IHIL E. NOVOTNY, OF PHTLADELPHIA, PENNSYLVANIA, ABSIGNOB TO JOHN STOG- DELL STOKES, 01; SPRING VALLEY FARMS, EUNTINGDON VALLEY' POST OFFICE,

PENNSYLVANIA PAPER PRODUCT AND PROCESS OI MAKING THE SAME No Drawing." Original application filed August 5, 1926, Serial No. 127,482. Divided and this application filed July 8, 1927.

This invention relates to plastics and lastic compositions and the process of ma ing the same. It is more particularly directed to the production of synthetic resin conden- 5 sation products of xylenols and formaldehyde of high dielectric strength and low moisture absorption and is preferably combined in such a manner that products of low viscosity and high penetrating power are obtained. The product is most particularly intended for use in the manufacture of sheet laminated materials of paper, cloth, etc., useful for electrical insulation and various mechanical structures but is most particularly directed to products of this kind where the requirements are for high dielectric values under adverse conditions of high humidit and heat. Products capable of meeting hig electrical tests under these adverse conditions are highly desirable and of great value under ordinary conditions of use.

This application is a division of my prior application, Serial No. 127,482, filed August 5, 1926, and entitled: Synthetic resins and 25 method of making the same.

The xylenols produce condensation products of high reactivity when condensed with an aldehyde, more particularly formaldehyde, without the use of a condensing or cata- 3 lytic agent. The reaction product made from these phenolic homologues and formaldehyde without the use of a condensing or catalytic agent gives resinous condensation products of great purity in that no extraneous materials need be used to carry out this reaction on a large commercial scale. When a catalyst is present in the reacting digester where this reaction is carried out, the final product is non-uniform in that certaln portions of the mass are carried over too far to give the most satisfactory results for this spe cial technical purpose. Where a basic catalyst is used even in small quantities as at present considered in the art of say one to two per cent of sodium or potassium carbonate or hyto control and the end product is evidently a mixture of highly reacted or polymerlzed condensation products with other products droxide, the reaction is extremely diilicult still in their uncombined state or in a rela- Serial No. 204,409.

tively loosely combined condition. Where the catalyst is reduced to say .01 of the quant1ty specified above ,or .01 to .02 per cent of the xylenol used the reaction requires precautions when digesting a large quantity of material at a time and there is present this trace'of hydrolyzable material which is objectionable in the final infusible roduct.

Where the reaction between t e xylenols and formaldehyde is carried out without the use of condensing agents the reaction is car-- ried out with precision and the only precaution necessary is to stop the reaction at the proper point when the materials have been sufliciently combinedand when a product of the desired viscosity has been obtained. This product gives values extremely low in moisture absorption, indicating free and uniform impregnation of the fibres and a thorough enveloping of these particles with the result that high dielectric strength is obtained. The use of kraft paper for laminated fiber structures offers many advantages because of its cheapness and strength. It is extremely difiicultto impregnate this material and great precautions are necessary to secure a paper having the right absorptive index in order that it may be used and that satisfactory physical and electrical values may be obtained in the laminated structure formed therefrom when impregnated with the usual phenol or cresol formaldehyde plus alkali condensation products. Although the xylenol is relatively cheap compared to phenol or good grades of meta and para cresol, it is capable of producing condensation products when combined with formaldehyde having a low viscosity and great penetrating power, and the final end products are high in dielectric and mechanical strength, and even in kraft paper the tensile split is very high.

It has been the contention that phenol-formaldehyde. condensation products made without a catal st react but slowly as, for example, in the tory British Patent No. 8875 of 1905. Note also paper read by Dr. Backeland before the New York section of the American Chemical Societon February 5, 1909, and published in the ournal of Industrial and Engineering Chemistry in 1909,

volume 1, pages 149 to 161, wherein he speaks of the slow reactivit of Storys product. However, during all t is discussion no mention is made that resinous condensation products of phenols or their homologues or more specifically the xylenols when reacted with formaldehyde would give products relatively superior in electrical properties than where these materials are made in the presence of a condensing agent. Resinous henolic condensation products lack many 0 the good attributes of other insulating materials and much of this deficiency is due to the use of catalysts or condensing agents.

It is true that the reaction between phenol and formaldehyde is quite slow when no condensing agent is used, but for certain purposes 1t is possible to produce commercial products of very high electrical value, although, of course, the reaction is somewhat slower. On the other hand, for certain purposes the reaction may be speeded by the use of high temperatures.

The xylenols, however, have higher boiling points than phenols and therefore the rate of reaction is greatly increased as will be noted in the example to be, given later. The reaction is usually carried out in from two to two and one-half hours which is a very convenient duration of time where lar e. commercial batches of material are ma e. On subsequent impregnation into a sheetlike product such as kraft paper it will be found that the loss in resin volatile substance is no greater than where a catalyst isused. Upon subsequently pressing the product under the usual temperatures, pressures and duration of time used for the roduction of products of this type hereto ore utilizing materials including catalytic agents, no increased time is required and the product assumes a hard, infusible, relatively insoluble form having high physical and electrical values.

By my choice of raw material and the carrying of the reaction through its resinous condensation cycle without a catalytic or condensing agent, it is possible to produce a synthetic resin product of xylenols and formaldehyde which has all the reactivity necessary for its use either as a varnish for incorporation into textile or paper products or as a solid resin to be ground and incorporated in various paper products at the beaters of the paper mill.

When this material is used for incorporation at the beaters of the paper mill it will be found, likewise, that the xylenols are much less soluble in water and that it is not at all necessary to first add additional phenolic bodies to the waters at the beaters in order to obviate the loss of xylenol which may be in a more or less free state within the resinous bod Evidently this has been found a desira 1e practice with certain types of phenolcresol-formaldehyde resins as has been brought out in some of the recent patent art. The elimination of this step simplifies the process of introducing a resinous product at the beaters of the paper mill as it is only necessary to introduce the proper proportion of this finely ground, comminuted resin at the beaters or thoroughly mix or commingle the same with the paper pulp or furnish. It is also found objectionable to use a hardening agent such as hexamethylenetetramine, first because the hexamethylenetetramine liberates large amountsof ammonia and certain of this ammonia becomes entrapped within the product and some combines with the resin forming a resinate. Secondly, hexamethlyenetetramine is readily soluble in water and therefore cannot be introduced at the beaters unless it had previously been combined with the resinous product.

Where the product is mixed with the paper pulp at the beaters or in the stufi chest the only precautions necessary are to make sure that the material is properly mixed with the fibres and that when formed in sheetlike form the temperature of the drying rolls or'drying tunnels be maintained well below the critical reacting temperature of the resin.

In order that my invention may be better understood, the following examples are given by way of illustration- Example 1 Xylenol, commercial grade 32 parts.

Formaldehyde, commercial grade 37 to 4.0 per cent strength 21.2 parts.

These materials are placed into a suitable digester equipped with an efficient stirrer and provided with a suitable condenser for distillation. With the condenser set in a distillation angle the product is boiled vigorously, stirring being maintained during the entire reaction and distillation c cle. There is evidently an immediate com ination between the xylenols and formaldehyde as there is only a trace of formaldehyde present in the distillate, moreover, the distillate has practically no formaldeh de odor. It should be noted particularly t at no step is called for in this process whereby a refluxing reaction is maintained during any portion of this cycle. The boiling and distillation is continued for about two hours or for such a length of time and under such conditions of temperature control, etc. until the desired viscosity or combination has been obtained. The reaction goes along smoothly and the removal of both the water of solution and condensation may be removed with little diificulty at ordinary atmospheric pressure as the reaction product is thin at the early stages of the reaction and as the solubility of water in xylenol is 'low.

From 15 to 18 parts ofdistillate will be removed dependin on the completeness of the reaction and on t e strength of the formaldehyde solution used. The temperature of the contents of the digester start boihng at about 212 F. and the temperature increases as the water is eliminated until a tem erature of 280 F. is preferably reached. t this temperature the product will be a hard grindable resin. For varnishes and gums an end temperature of from 250 F. to 270 F. will produce a desirable product. With vacuum distillation at the end of the reaction or say after a temperature of 250 F. has been reached a hard resin can be obtained on large batches with less precautions.

Although no refluxing has been carried out as previously stated there is less loss of reagents than if the reaction were carried out under reflux conditions. Under this method of operation the contact between the two reagents, i. e., x lenol and formaldehyde, is better because 0 the elimination of the water of reaction as the condensation progresses. It will be noted that the proportion oft-he reagents used as proximately in e ual molecular proportion and that the resin oes not remain permanently fusible, and that, therefore, there is no appreciable loss of formaldehyde when xyleno s are used and that no contracting pressure or refluxing is necessary to retain the predetermined amount of reagent proportions.

So far as the proportion of reagents -is concerned a wide variation is possible, that is, an excess of formaldehyde will take care of itself by either a further combination or will be eliminated during the subsequent drying or processing operations,-and so far as the xylenols are concerned they will likewise be evaporated or driven off so that under proper drying conditions a wider variation in the proportion of the reagent can be used and still final infusible substantially insoluble product may be obtained when the final hardening reaction is carried out. This statement also applies to Example N o. 2 given below. This example is given as illustrative of the reaction carried out under conditions of reliminary refluxing and subsequent distillation.

Ewample 2.

Xylenol, commercial grade, 61 parts.

Formaldehyde, commercial grade 37 to 40%, 40.5 parts.

These materials are placed into a suitable digester equipped with a condenser for both reflux and distillation. The product is boiled under reflux for from two to two and one-quarter hours, stirring rapidly until a product of the desired viscosity is obtained. Adjust condenser for distillation and distill to remove as much water as possible. When a temperature of 300 F. has been reached the product will be ready for use if a varnish is to be manufactured, or, in other words, the

given in this example 1s apresin will be of relatively low viscosity and low meltin point. If the distillation is conducted un era vacuum a solid resin will be obtained at somewhat lower temperature.

Under the proportions as 'ven the water of solution would consist 0 approximately 25.5 parts and the water of reaction 9.0 arts or'a total water content of 34.5 parts. ere the varnish is reduced without vacuum distillation it wil be found that the total Water distilled will not reatly exceed 31 Some water of con ensation is still inc uded in the ,mass and some of the reacting materials have not been entirely combined, but this has no undesirable objections where relatively thin sheets are im regnated in varnish form and dried thoroughly subsequent to the final pressing operation.

To this material while still hot and with the condenser setat the reflux position, I add alcohol 24 parts and furfural 2 parts. The alcohol is added in order to obtain a thin mass which may be readily used for impregnation and additional quantities of alcohol may be added if necessary before the material is used.

To the gums or resins made according to the process disclosures given in either examples one or two various hardening agents may be added such as, for example, hexamethylenetetramine. polymerized formaldehyde or various bodies having active methylene groups in condition to combine with the resinous products or'for that matter other aldehydes or their derivatives such as fur-' fural orfurfuramid. The is complete in itself and no hardening agent is necessary unless it be used more in the nature of-an accelerating agent in order to promote the speed or lower the tem erature at which the reaction is brought to a nal infusible form.

The furfural is added for the purpose of acting as a neutral final hardening agent assisting in converting the resinous product upon final pressing to its final hard and-infusible form. In the place of furfural a neutral well washed furfuramid may be added in from one to ten per cent of the weight of the resin solids. This furfuramid, however, where the product is to be used for the highest grade of electrical structure, is objectionable as it breaks down to furan'e, 'furfural and ammonia. Likewise, hexamethylenetetramine can be used as a hardening agent, but this also is objectionable because of the ammonia liberated.

The use of a hardening agent is not essential as the material is complete in itself and will upon subsequent heating go to the infusible, substantially insoluble state. There is no objection, however, to the use of furfural itself as the product is neutral and will not affect the dielectric properties of the synthetic resin. V

arts.

product, however,

Various coloring materials, dyes, pigments, etc., the dyes preferably soluble in the solvents used and the pigments preferably in colloidal suspension, may be added before, during or at the end of the reaction. Various modifying agents may be added such as camphor, oil of camphor, lanolin, or China wood oil. These modifying agents are usually added throu h the use of other solvents than alcohol as, %or exam 1e, where lanolin is used this is added in a dissolved state with benzol. Where China wood oil is used this is preferably added by using about twice the weight of the China wood oil in furfural, benzol or carbon tetrachloride. These modifying agents tend to make the material more plastic so it may be more readily machined, cut, punched, etc., when in the cold state.

Various lubricants may be added such as, for example, a quantity of camphor, stearic acid, or calcium stearate.

Wherein I have called for the use of xylenol it is to be understood that the commercial grade of xylenols include certain lower boiling fractions and certain higher boiling fractions which are in no way detrimental for my purpose. It is, of course, also evident that the use of xylenols bcause of their high boiling range and excellent resin solvent properties and tendency to form a gel makes them useful when added in various proportions to other phenolic bodies and therefore, it is to be understood that I wish this use included wherein I claim the use of xylenols.

Wherein I have called for, the use of formaldehyde or aqueous solution of formaldehyde it is to be understood that I can use formaldehyde merized forma dehyde or other useful substances having active methylene groups in condition to combine with either the xylenols or the resinous condensation products produced from them. It is, however, to be noted that theinvention of this specification is the use of an active methylene body which will not liberate undesirable bases or acids whereby the electrical properties of the product would be impaired.

Wherein I have shown that the resin is preferably alcohol soluble it is to be understood that this material is soluble in various other organic solvents such as acetone, furfural, etc. or a mixture of alcohol and benzol in various proportions or, for that matter, a mixture of benzol and furfural may be used as solvents for this resinous product. The resinous products, on the other hand, may be reacted to the point where they are no longer soluble in alcohol but require certain higher solvents such as, for example, acetone or furfural, or mixtures of these. These resinous products when no longer soluble in alcohol are more highly polymerized and the penetration of varnish solvents may as or various forms of polybe regulated by the degree of preliminary polymerization.

It is to be understood that these resinous condensation products of xylenols and formaldehyde are soluble in 15% alkaline solutions such as sodium or potassium hydroxide and that they are precipitated out of solution by the use of a suitable quantity of acid or, for that matter, by alum such as ordinary potassium alum. These resinous products when in suitable form either in solution or in finely comminuted particles, may be incorporated with various spun or woven textile or paper products at the time such products are belng formed or at any preferred time thereafter. When so combined with these textile products they act as reinforcing cementitious materials which may be subsequentl reacted under heat or heat and pressure to their final infusible form. For certain classes of work where solvent recovery is not possible it is preferable to introduce these resinous products into these textile or paper products by direct incorporation methods at a considerable savin in solvent cost.

While t e synthetic resin products made of xylenols or mixtures or other phenolic bodies with xylenol and formaldehyde are particularly well adapted for use in making laminated paper and textile products, they are also useful for the manufacture of comminuted molding powders when mixed or incorporated with suitable organic or inorganic fillers, plasticisers and modifying agents.

These synthetic resin products when in solution as a varnish mix well with pyroxylin products producing lacquers of a very desirable quality.- As the synthetic resin products polymerize gradually at ordinar room temperature the film of pyroxylin lac uer becomes stronger and tougher with age. he resinous product furthermore leaves a glossy,

shiny film, does not weaken, and increases the adhesion ofithe film to the supporting body. It has an outstanding desirable property in that when used in various quantities and even when used in small quantities it reduces the viscosity of the lacquer to such an extent that a relatively high viscosity nitrocellulose can be used and products of relatively high solids content and low viscosit can be obtained when in solution in suite le solvents. This is particularly true when some of the furfural has been caused to combine with the xylenol formaldehyde resin but the resin without the furfural added will have these same desirable properties but to a somewhat lesser extent.

,What I claim isv 1. A paper like body having incorporated therewith a resinous reaction product of but two substances, namely: xylenol and formaldehyde, said product comprising a potentially reactive, fusible, resinous compound.

2. A paper like body having incorporated therewith a resinous reaction productof but two substances, namely: a phenolic body and formaldehyde and having furfural added thereto.

3. A paper like body having incorporated therewith a resinous reaction product of but two substances, namely; a phenolic body and formaldehyde and having added thereto a fur-fural derivative. Y

4. A reaction product of but two substances, namely: xylenol and formaldehyde,

said product comprising a fusible resinous body incorporated in paper pulp durin the manufacture of said paper like body wit out material loss of the orlginal resin forming.

ingredients.

5. A resinous reaction product of but two substances, namely: xylenol and formaldehyde, incorporatedin paper pulp durin the manufacture of said paper like body wit out material loss of the original resin forming ingredients, and containing furfural.

6. The herein described steps in the process of making a fusible resinous reaction product of xylenols and formaldehyde comprising the incorporation of this resinous product with a fibrous material during the process of fabrication of said fibrous material into a spun,

woven or sheet-like form and subsequently shaping and hardening the same through the 7 action of heat and pressure to convert said resinous body into its infusible form.

7. The herein described method of making a moldable compound comprising a reaction product of but two substances, namely; xylenols and formaldehyde said reaction product being incorporated with suitable brous material during the process of fabricating such fibrous materialinto a sheetlike form and adding thereto an aldehyde such as furfural;

8. The herein described process of making a potentially reactive plastic com rising incorporating axylenol-formaldehy e reaction product made without the aid of a catalyst or hardening agent other than furfural, and incorporating said reaction product in a fibrous, spinnable material during the opera-, tion of forming said fibrous material into the desired form without undue loss of reagents in order that the potential reactivity of the resinous mass will not be reduced.

Signed at- Philadelphia in the county of Philadelphia and State of Pennsylvania this eighth day of June A.-D.,1927. f

, EM1L E. NOVOTNY. 

